Catheter ablation of atrioventricular nodal reentrant tachycardia, when AVNRT presented as a fetus or infant.

BACKGROUND: Atrioventricular nodal reentrant tachycardia (AVNRT) does not commonly present during infancy. Although relative safety of catheter ablation of AVNRT has been demonstrated in pediatrics, this procedure is rarely indicated in children <15 kg. METHODS: Retrospective review of seven cases of AVNRT that presented in children younger than 1 year of age and required catheter ablation for definitive management. Electrophysiology (EP) study was planned with two or three catheters. Area of ablation determined by voltage mapping, propagation sinus wave collision and slow pathway potential location. Ablation performed with cryothermal energy. No fluoroscopy was used. RESULTS: Presentation ranged from 36 weeks of gestation to 11 months of age. Two presented in fetal life and two in the neonatal period. The median age of ablation was 20 months (range 17-31 months). The median weight at ablation was 11.4 kg (range 8.9-14.9 kg). Median follow-up time was 16 months. All had typical AVNRT. The median tachycardia cycle length was 216 ms. 100% successful rate using cryoablation. No complications. No recurrence of tachycardia during the follow-up period. CONCLUSION: Slow AV nodal pathway cryoablation may be safely performed, with good short and medium-term outcomes in patients under 15 kg.

Pediatric Micra leadless pacemaker implantation via internal jugular and femoral veins: experience with 11 patients.

In pediatrics, conventional transvenous and epicardial pacemaker systems carry complications, such as lead distortion due to growth and activity, in addition to lead and pocket complications. A retrospective review of pediatric leadless pacing at the University of Minnesota Masonic Children's Hospital (MN, USA) from 2018 through 2021 was performed. Diagnoses, rationale for pacing, demographics, pacing thresholds and longevity of devices were recorded. Twelve leadless pacemaker insertions and one removal were performed successfully in patients weighing 19-90 kg. Six patients had Micra implantation via the internal jugular vein without surgical cut-down. Up to 3 years of follow-up were noted, with median follow-up of 22 months. No late complications occurred. Leadless pacemaker implantation and early retrieval were feasible in pediatric patients.

Pacemaker placement has been the standard of care for patients when the top and bottom chambers of the heart are not communicating electrically. Patients can either be born with this, or it can happen after heart surgery. Traditional pacemaker technique involves placing wires (leads) through veins to the heart and surgically implanting a generator in the body. This carries a risk of complications, mainly lead dislocation and fracture with growth and activity. The Micra leadless pacemaker mitigates this risk and can be implanted into the muscle of the right ventricle. There are currently only small case series and reports in the literature on Micra pacemaker implantation in pediatric patients with congenital heart disease. We implanted 12 such devices in 11 pediatric patients weighing 19­90 kg. Six of these implantations were deployed using the internal jugular vein and were successful. One patient had a pericardial effusion at the time of implantation. Overall, leadless pacemaker implantation in the pediatric population with congenital heart disease is feasible, but further data are needed to assess long-term safety.

Is derived vectorcardiography a potential screening tool for pulmonary hypertension?

BACKGROUND: Patients with atrial septal defects and pulmonary hypertension would benefit from early identification and treatment of pulmonary hypertension prior to closure. Noninvasive screening tools for pulmonary hypertension are inadequate. Electrocardiography, though readily available, has so far been of limited screening utility in patients with pulmonary hypertension. We hypothesize that derived vectorcardiographic parameters will aid in identifying increased right ventricular afterload and thus provide an additional screening tool for pulmonary hypertension in patients with secundum atrial septal defects. OBJECTIVE: Establish whether vectorcardiography can be used to screen for pulmonary hypertension. METHODS: A retrospective review of patients with secundum atrial septal defects (ASD) who underwent cardiac catheterization at the University of Minnesota from 2012 to 2020 was performed. We excluded patients with other congenital heart diagnoses, insufficient hemodynamic data, or lacking sinus rhythm electrocardiogram at time of cardiac catheterization. Parameters analyzed included: Sokolow-Lion right ventricular hypertrophy criteria, PR duration, QRS duration, corrected QT intervals, QRS and T wave frontal plane axes, rSR', R' amplitude, as well as vectorcardiographic parameters (Kors regression-related method), the QRS vector magnitude, T wave vector magnitude, and the spatial QRS-T angle. These were compared to measures of pulmonary hypertension obtained at cardiac catheterization. RESULTS: The spatial QRS-T angle significantly differentiated ASD patients with pulmonary hypertension (median 104 degrees, interquartile range 55-137 degrees) from ASD patients without pulmonary hypertension (median 37 degrees, interquartile range 21-63 degrees, p-value of 0.002). At a cut-off of 124 degrees, the positive and negative predictive values for identification of pulmonary hypertension were 36.4% and 96.4%, respectively, with an odds ratio of 13.4 (95% confidence interval of 2.9 to 63.7). The positive predictive value was significantly improved when combined with echocardiographic data to screen for pulmonary hypertension. CONCLUSION: The spatial QRS-T angle is associated with pulmonary hypertension in patients with secundum atrial septal defects.

Vectorcardiography as a prognostic tool in hypertrophic cardiomyopathy.

BACKGROUND: Vectorcardiography (VCG) has demonstrated diagnostic value in the assessment of hypertrophic cardiomyopathy (HCM), however, determining its prognostic value over time has not yet been investigated. This study sought to assess the correlation of VCG parameters with the progression of HCM. METHODS: A retrospective chart review of 119 pediatric patients with diagnosis of HCM at the University of Minnesota. Eighty-three cases were excluded because of age, presence of congenital heart disease, not meeting criteria for HCM or negative phenotype. Sample was divided into 2 groups based on the presence or not of cardiac events (ventricular tachycardia, cardiac arrest, ventricular assist device, heart transplant). Derived vectorcardiography from standard 12­lead ECG was obtained for the first ECG and last available or prior to sentinel event. RESULTS: Of the 36 cases that met inclusion criteria, 9 (25%) developed a sentinel event. The median age for the event group was 10.1 ± 7.5 years and for the non-event group was 8.7 ± 6.35 years. There was no significant difference in age or sex between the groups. The T wave vector magnitude value was significantly smaller in the event group than in the non-event group (0.302 ± 0.146 mV Vs. 0.561 ± 0.305 mV, p 0.002), with a hazard ratio of 0.651 (95% CI 0.463 to 0.915). No other parameter showed significant difference between the two groups. CONCLUSIONS: The T wave vector magnitude may predict sentinel events in HCM. Prospective studies are necessary to evaluate the utility of the evolution of VCG parameters.